Figure 3

Effect of exposure time on the absolute (A–C) and relative (D–F) LSCI sensitivity to the flow change according to theoretical calculations. The blue lines correspond to the original derivations by Yuan et al.²⁹, while red and yellow lines correspond to the calculations made with respective contrast models for large (\(\tau _c=75 \; \upmu \text{s}\), Eq. (3)) and medium (\(\tau _c=150 \; \upmu \text{s}\), Eq. (4)) vessels and parenchyma (\(\tau _c=250 \; \upmu \text{s}\), Eq. (5)). For the simplified (red lines) model parameterization, the \(\rho \) and C parameters were set to 1 and 0, independent of the simulated vessel type. For the realistic (yellow lines) model parameterization, C was set to 0.01 for all simulated vessel types, while \(\rho \) was set to 1 in large and medium vessels and 0.8 in the parenchyma. It is vital to notice that not only the sensitivity curves are altered depending on the vessel type but that the presence of noise or static scattering (\(C>0\) or \(\rho <1\)) leads to a decrease in the relative sensitivity after \(T/\tau _C\) reaches the value of \(\approx \)10–15.